The present application discloses a variable speed lathe having a sliding, horizontally-rotatable headstock. The present variable speed lathe is less complicated and expensive than typical prior art variable speed lathes which comprise typical prior art variable speed pulleys and/or typical prior art variable speed drive systems. Furthermore, in a preferred embodiment, one or more of the variable speed pulleys of the variable speed drive system within the lathe may comprise a conical face which extends substantially to the diameter of the central aperture. In such an embodiment, a greater range of speeds can be obtained for the same pulley size than can be obtained in typical prior art variable speed lathes which comprise typical prior art variable speed drive systems having variable speed pulleys in which the sheaves are positioned onto one or more sleeves and/or other hardware for supporting and interconnecting the sheaves.
The preferred lathe comprises a lathe bed and a headstock positioned on the lathe bed. The headstock comprises a variable speed system including two variable speed pulleys formed by sheaves, a driving shaft and a driven spindle shaft. Support means associated with the headstock operationally supports the two shafts in positions substantially parallel to one another. A V belt operationally connects the two pulleys.
Each variable speed pulley comprises two fixed sheaves, one on each shaft. Each fixed sheave comprises a conical face for forming one V belt bearing surface. The fixed sheaves further comprise means for securing the sheaves onto the driving or driven shaft so that the sheaves are prevented from both axial and rotational movement on the shafts. The means for securing each fixed sheave comprises a central aperture defined by a surface of the sheave. The central aperture has a diameter substantially corresponding to the diameter of the shaft so that the surface of the sheave which defines the central aperture is configured to be in direct contact with the shaft when the sheave is positioned on the shaft. The fixed sheave on the driving shaft and the fixed sheave on the driven shaft are positioned so that a tracking plane of the V belt is established to be substantially perpendicular to the axis of each shaft.
Each variable speed pulley also comprises first and second moveable sheaves, one on each shaft. Each moveable sheave comprises a conical face for forming one V belt bearing surface. The moveable sheaves further comprise means for securing the sheaves onto the driving or driven shaft so that the sheaves may move in the axial direction while being prevented from rotational movement on the shaft. The means for securing each moveable sheave comprises a central aperture defined by a surface of the sheave, the central aperture having a diameter substantially corresponding to the diameter of the shaft so that the surface of the sheave which defines the central aperture is configured to be in slidable direct contact with the shaft when the sheave is positioned on the shaft.
The present lathe further comprises control means for controlling the position of each moveable sheave so that the speed of the lathe spindle shaft can be controlled.
The preferred lathe comprises a slidable, horizontally-rotatable headstock. The lathe comprises a lathe bed having a length along a longitudinal axis. The lathe bed comprises rails oriented parallel to the longitudinal axis. The rails define a horizontal plane. The lathe bed has a side in front of which a user normally stands.
A headstock is located on the lathe bed rails. The headstock comprises a spindle shaft having a stock turning end for providing rotational movement to stock to be turned on the lathe. The spindle shaft has a length along a central axis. The central axis of the spindle shaft is located a predetermined distance above the rails. The headstock further comprises an adjustment mechanism for selectively adjusting the orientation of the spindle shaft axis in at least two orientations including parallel to the longitudinal axis of the lathe bed or perpendicular to the longitudinal axis of the lathe bed. The spindle shaft axis in each orientation is parallel to the horizontal plane defined by the rails.
The adjustment mechanism further comprises means for slidably locating the headstock along the length of the lathe bed so that, when the headstock is oriented in the second orientation with the stock turning end of the spindle shaft turned toward the front side of the lathe bed, stock which is too large in diameter to be turned between the central axis of the spindle shaft and the rails can be turned on the front side of the lathe bed with the headstock located substantially in the center of the bed in order to achieve maximum stability of the lathe while turning.
In its preferred form, the headstock comprises a surface which rests on the rails, and the surface which rests on the rails defines first and second mutually perpendicular slots formed in the bottom of the base. The lathe bed comprises a clamp key which fits between the rails and into the first and second slots. The clamp key comprises means for securing the headstock to the rails so that the spindle shaft can be oriented in either of the two mutually perpendicular orientations anywhere along the length of the lathe bed.